Froth flotation of nonmetallic minerals



Patented July 29, 1941 OFFICE ,FROTH FLOTATION F NONMETALLIC MINERALS Julius Bruce Clennner and Carl Bampacek, Tuscaloosa, Ala.

No Drawing. Application May 1, 1945, Serial No. 591,293

8 Claims. (Cl. 209-166) (Granted under the amended April 30, 1928;

The invention described herein may be manufactured and used by or for the Government of the United States for governmental purposes without the payment to us of any royalty thereon in accordance with the provisions of the act of April 30, 1928 (Ch. 460, 45 Stat. L 467).

This invention relates to an improved process for the concentration of nonmetallic minerals from ores containing them in association with siliceous gangue; more particularly it relates to a froth flotation process employing anionic collecting agents to effect flotation of activated siliceous gangue constituents from nonmetallic ores. The term nonmetallic is used herein to designate those minerals which are used commercially for purposes other than as a source of metal which they contain. Among the so designated nonmetallic minerals are included phosphates, calcite, barite, strontianite, and witherite. The present invention herein described relates to the froth flotation of activated siliceous gangue constituents from all five of these minerals.

An object of the invention is to provide an improved process for the concentration of nonmetallic minerals in pulps containing them in the presence of siliceous gangue. A further object is to provide a flotation process which will have greater selectivity in separating siliceous materials from nonmetallic ores and thereby effect greater operating economies. A still further object is to provide a frothflotation process for siliceous gangue materials wherein inexpensive anionic collecting agents are employed to float the siliceous gangue. Other objects, purposes, and advantages of the invention will hereinafter more fully appear or will be understood from the detailed description of its practice.

We are aware that various froth flotation methods have been proposed for the concentration of nonmetallic ores for the purpose of rejecting siliceous gangue constituents and recovering an enriched product of the economic nonmetallic minerals. A conventional flotation method well known to the art is to float the economic nonmetallic minerals from the siliceous gangue materials employing oleic acid, sodium oleate, or similar anionic collecting agents in conjunction with various addition agents in acid, neutral, or moderately aklaline pulps to facilitate flotation of the desired nonmetallic mineral from the retarded silica. The technical and patent literature abounds with examples of practice of the methods for the flotation of such nonmetallic minerals as rock phosphate, calcite, barite, and fluorspar from quartz, feldspar, and other siliceous gangue materials. Among others, for example, Crago describes a method for the anionic flotation of act of March 3, 1883, as

fluorspar or phosphate rock from siliceous gangue in U. S. Patent 2,105,807. Tartaron in U. S. Patent 2,105,826 makes use of the short chain fatty acid collectors and various metal salts to effect flotation of phosphate rock, calcite, barite, or fluorspar from siliceous gangue in substantially neutral or acid pulps. Rose and MacDonald'in U. S. Patent 2,040,187 describes the flotation of carbonates, sulfates, fluorides, tungstates, and oxides from each other and from siliceous gangue by the use of fatty acid collecting agents in conjunction with various metallic salts in the presence of a metaphosphate or similar addition agent. These and numerous other investigators have made use of various anionic collectors in conjunction with a variety of inorganic and organic addition agents to enable flotation of nonsulfide metallic and nonmetallic minerals from each other and from siliceous gangue in particular.

An alternative method for concentrating nonmetallic minerals by flotation is to reverse the customary separation and float the siliceous gangue constituents from the nonmetallic carbonate, sulfate, or phosphate minerals employing cationic collecting agents such as laurylamine hydrochloride, cetyl trimethyl ammonium bromide, or similar compounds which ionize in the aqueous pulps to yield a large active cation. Collectors of the cationic type have been used and found advantageous for the flotation of siliceous gangue from many nonmetallic ores. Among others, for example, Tartaron describes a method for the cationic flotation of silica from phosphates, calcite, barite, and fluorspar in U. S. Patent 2,222,728 and Breerwood and Williams in U. S. Patent 2,161,010 made use of cationic collectors for floating siliceous constituents from cement rock. Despite their widespread adoption for the flotation of silica and silicates from non-sulfide and nonmetallic ores and mineral products, cationic collectors have many limitations. They are more expensive than collectors of the anionic type, and, moreover, they are not particularly selective. Cationic collectors are ineffective silica collectors in the presence of slime and desliming of the ore pulp is generally necessary before satisfactory flotation separation can be achieved.

As a result of extended research and experimentation, we have discovered a method of concentrating nonmetallic ores by froth flotation wherein anionic collecting agents are employed to float activated siliceous gangue constituents from caustic alkaline ore pulps with a pH of at least 10 while retarding flotation of the economic nonmetallic mineral with a soluble inorganic metaphosphate or polyphosphate. A moderate quanssame assignee as the present application,

.tain naturally activated siliceous tity of a metaor poly-phosphate in a strongly caustic alkaline pulp of the non-metallic ore effectively retards flotation of such nonmetallic minerals as calcium phosphate in phosphate rock, calcite in cement rock, and barite, strontianite. or witherite without adversely affecting anionic flotation of the activated silica.

In a co-pending application, assigned to tLie 7 Julius Bruce Clemmer and Ballard H. Clemmo Serial No. 473,162, flied January 22, 1943, scribed a process for beneiiciating iron ores and products from themilling of iron ores containing calcareous and/or siliceous gangue materials wherein anionic collecting agents are employed to float the activated siliceous constituents from caustic alkaline iron ore pulps with a pH of at least 10 while retarding flotation of the iron oxides with a metaphosphate or polyphosphate. Choice of the quantity of phosphate and collector employed in flotation of the calcareous iron ores enables flotation of the calcareous constituents with the activated silica or retardation of the,

calcareous materials with the iron oxides. The present application is an outgrowth of the aforementioned invention with particular reference to the concentration of nonmetallic ores and mineral products.

A caustic alkaline pulp with a pH at least as high as 10, and preferably in the pH range 10 to 12, is preferable in our method of flotation to facilitate effective retardation of the economic nonmetallic minerals by the metaor poly-phosphate depressants during flotation of the silica. We prefer to employ caustic alkalies, such as sodium or potassium hydroxides, or their equivalents, to establish the desired pH for flotation. Moderate quantities of other alkaline reagents, such as sodium sulfide, sodium carbonate, and sodium silicate, may be used in conjunction with the caustic alkalies if desired. A combination of hydrated lime and soda ash has been successfully employed in the flotation of many nonmetallic ores and served the dual purpose of activating the siliceous materials to anionic flotation and establishing the desired caustic alkalinity for flotation by formation of caustic soda within the pulp. The optimum pH for anionic flotation of the activated siliceous constituents and retardation of the desired nonmetallic mineral to be recovered varies slightly for diflerent ores but generally falls within the range 10 to 12, and the proper pH for any particular case is'best determined by experimentation. Poor flotation of the silica and incomplete retardation of the nonmetallic invariably results if the pH of the pulp is much less than 10; a pulp pH greater than 12 is not particularly objectionable in our method of flotation, but the froth is inclined to be voluminous and flotation of the silica is sluggish. We, therefore, prefer in our flotation method to keep the pH in the range of 10 to 12.

It is essential in the practice of this invention that the siliceous gangue constituents in the nonmetallic ore be activated and rendered floatable. The siliceous gangue materials in certain nonmetallic ores, such as the cement rocks containing quartz associated with calcite or limestone, are naturally activated to soap flotation, presumedly due to soluble calcium salts in the ore. Other nonmetallic ores, however, seldom conmaterials and the successful operation of our process requires that the silica in such ores be activated for anionic flotation. Extended research of a variety isdewashing the pulp with of nonmetallic Ores demonstrated that on method of flotation lends itself readily to the us of silica activating agents. Many alkaline-cart! and heavy metal salts exhibit the property of acti vatingquartz and various silicate minerals ti soap flotation when a proper quantity is employer at an optimum pH. We have found that condi tioning of the caustic alkaline ore pulp with 5 moderate quantity of an activator selected iron the group consisting of soluble calcium, magnesium, barium, strontium, and lead salts sufllce: to activate the siliceous gangue constituents in many nonmetallic ores to anionic flotation by the higher fatty acids. resin acids, or their derived soaps, without adversely aii'ecting retardation oi the economic nonmetallic mineral by the phosphate depressants. The effectiveness of the metal salt activating agents differs for difl'erent ores and the proper quantity for any particular case is best determined by experimentation. A proper quantity of metal salt activating agent, collector, and phosphate depressant in a caustic alkaline pulp with a pH of 10 to 12 enables rapid and substantially complete flotation of silica form calcium phosphate. calcite, barite, strontianite, or witherite.

We may also employ hydrated lime as the silica activating agent in the practice of our invention, and from the standpoint of cost, hydrated lime is particularly attractive. Grinding or blunging the ore with suiflcient hydrated lime to establish a pulp pH of about 11 effects substantially complete activation of the silica. The usual quantity of hydrated lime required to activate the silica varies from 1 to 4 pounds per ton of ore, but some ores containing acidic salts may require 8 pounds or more of lime perton. Excessive quantitle of dissolved hydrated lime in the conditioned pulp should be removed before flotation as they increase collector and phosphate requirements. Although we have achieved by the practice of our invention good flotation of silica from .nonmetallic ore pulps containing as much as parts per million of hydrated lime in solution, equivalent in our tests to about 0.8 pound of hydrated lime per ton of solids, we prefer that the pulp for flotation be substantially free of dissolved hydrated lime. The lime salts in the conditioned pulp may be removed by settling and fresh water, or by addition of suflicient soda ash to the pulp to precipitate the disolved lime as insoluble calcium carbonate. The combination of hydrated lime and soda ash was particularly advantageous on many ores; conditioning the ore pulp with hydrated lime to give a pH of about 11 sufllced for activation of the silica and subsequent addition of soda ash to precipitate the dissolved hydrated lime remaining in solution gave a pulp of the desired caustic alkalinity for flotation. Additional caustic soda may be added to the pulp if desired. Should an excess of hydrated lime be inadvertently added to the pulp to activate the silica, as evidenced by a pH of about 12.3 which is the pH of a saturated solution of hydrated lime, the excess is best removed by settling and washing the pulp one or more times with fresh water to reduce the pH to about 11, whereupon soda ash may be added to precipitate the dissolved lime remaining in the pulp before proceeding with flotation. If desired. however, the washing may be carried further to give a flnal pulp for flotation practically free of dissolved hydrated lime and having a pH of 9 to 10. Subsequent addition of a caustic alkali to the lime conditioned and washed pulp to establish the desired pH for flotation together with a higher fatty acid, resin acid, or soap collecting agent in conjunction with a metaphosphate or polyphosphate enables flotation of the calciumactivated silica and retardation of the economic nonmetallic mineral.

The use of a soft water free of lime or magnesia salts is not obligatory in the practice of this invention. A water moderately hard with lime salts, for example: is permisible and, in fact, has been found advantageous as the lime salts aid in the activation of the siliceous materials.

The anionic collecting agents which we have found suitable for flotation of activated siliceous gangue materials from nonmetallic ores include oieic acid, red oil (crude oleic acid), crude and purified sodium oleate, fish oil fatty acids, fish oil soaps, and various crude or purified tallols and sulfate soaps recovered from sulfate paper mill black liquors. The tallols, which are mixture of fatty and resin acids, are relatively inexpensive and are particularly attractive collectors on many nonmetallic ores.

The various phosphates which we have employed andfound suitable for retarding flotation of nonmetallic minerals in the practice of our invention include sodium metaphosphate, sodium hexametaphosphate, and sodium tetra-phosphate. The potassium salts may also be employed if desired, but they are more expensive than the sodium salts. The alkali-metal salts of the orthoand pyro-phosphates lack the specific depressing properties of the metaand poly-phosphates, but have been employed as auxiliary reagents in the practice of our invention to aid pulp dispersion and improve the flotation separation.

While we have achieved satisfactory flotation of activated silica from nonmetallic ore pulps containing substantial quantities of slime by the practice of our invention, we prefer that the flotation pulp be deslimed. Desliming of the pulp should be practiced whenever permissible as subsequent flotation of the activated silica is more rapid and complete, and less reagents are required in flotation.

The proportions of the various reagents employed in the practice of our flotation method are subject to considerable variation, and the optimum quantities are best determined by experimentation for any particular case. Purity of the separated products is a. reliable guide for reagent adjustment. An excess of collecting agent promotes flotation of a portion of the economic nonmetallic mineral with the activated siliceous gangue, whereas a deficiency of collector results in incomplete flotation of the silica. Conversely, an excess of metaphosphate or polyphosphate results in retardation of a portion of the siliceous gangue, whereas a deficiency permits flotation of the economic nonmetallic mineral with the silica. Control of the collector and phosphate depressant is not critical, however, and reasonable variations in the quantities employed is permissible without adversely affecting the separation.

Conventional flotation terminology designates the floated product from roughing and cleaning operations as concentrates, and the pulp residues as tailings and middlings, respectively. This terminology is in keeping with the general practice of floating the valuable mineral from the worthless gangue. When the separation is reversed and the gangue is floated from the economic mineral, the terminology may become con fused. To avoid possible confusion in describing the results of our flotation tests, we shall hereinafter designate the enriched pulps of the economic nonmetallic mineral from the roughing and cleaning steps as concentrates, rougher and concentrates, cleaner, respectively. The floated silica products from the roughing and cleaning steps will be designated as ,rougher froth" and "silica rejects, respectively. In describing the results of our flotation tests we shell for simplicity hereinafter consider and report the enriched pulps from the cleaning steps (middlings) as finished concentrates. It will be readily apparent to those skilled in the art that the middlings may be retreated by conventional methods to yield an even higher grade concentrate without departing from the spirit of the invention.

The invention will be further illustrated, but is not intended to be limited by the following examples of practice:'

Example I A sample of deslimed phosphate feed was obtained from an operating washer near Brewster, Florida, in the land-pebble phosphate district. The sample consisted mainly of so-called bone phosphate of lime (tricalcium phosphate) associated with quartz and some indurated clay. A head analysis gave 59.3 percent Caa(P0'4) 2, hereinafter referred to as B. P. L. for convenience, and 19.6 percent SiOz. The sample as received was substantially finer than 20 mesh and was used for the following flotation procedures.

A 250-gram portion of the phosphate sample was wet ground to pass 65 mesh in a laboratory pebble mill. The ground charge was diluted to a volume of 2.5 liters with additional tap water to give a pulp containing about 10 percent solids. The pulp was dispersed using caustic soda and sodium hexametaphosphate equivalent to 1.0 and 0.5 pound per ton of ore, respectively. 'llhe dispersed pulp was fractionated by sedimentation and decantation to remove the bulk of the slime finer than 20 microns. The deslimed granular portion of the ore was repulped with additional tap water and transferred to a small mechanical agitation flotation cell of standard design. Additional tap water was added to the cell to give a pulp for flotation containing about 20 percent solids. Flotation of the siliceous gangue from the calicum phosphate was achieved by employing the following reagent charge expressed in conventional pounds per ton of ore:

Conditioner R h S Cleaner oug cav- Reagent er enger No. 1 No. 2 N0. 1 No. 2

Caustic soda 1.5 0.5 0.5 Sodium hexametaphosphate 1.0 0. 04 'Ialiol 0. 6 0. 4 0. 4 0. 2 l. 0 0. 2 2. 5 3.0 3.0 3. 0 2. 5 10.6 10. 4 10.0 10. 2 l0. 2

The substantially deslimed pulp was first conditioned with the caustic soda (commercial lye) and sodium hexametaphosphate to retard the calcium phosphate and establish the desired caustic alkalinity for activation and flotation of the silica. The pulp was then conditioned with calcium chloride and talloi to activate and float the silica. Air was then allowed to enter the cell and resulted in immediate formation of a compact, heavily mineralized froth of the si liceous gangue materials. The froth was collected for 3.0 minutes whereupon flotation of the collecting the resulting froth for plete. Additional tallol was then added to the pulp and a scavenger product was obtained by The rougherandscavenger frothswerecombined activate and float the remaining silica in a and cleaned twice by refloating in the same cell scavenger froth. The rougher and scavenger using ta water for dilution and the quantities froths were combined and cleaned twice by reof reagents as indicated. The flnal silica rejects, floating in the same cell. Tap water was used the combined phosphate concentrates from the for dilution together with the quantities of recleaning steps (middlings), the rougher phosagentsasindicated. Therougher and composited phate concentrate (tailing), and the untreated cleaner phosphate concentrates, and the flnal slime were dried, weighed, and analyzed. The silica rejects were dried, weighed, and analyzed. results of the test are as follows. The results of the test are as follows:

Product weight Assay, percent Dish, per cent mm wow, Assay,percent Dist... per cent percent DUN! B. P. L. 010, B. P. L. 010, B. P. L. s10, B. P. L. 010,

Phosphate Concen- Phosphate Concentrates: tratss:

Rougher 03.2 01.0 a2 72.1 20.0 Rougher 40.2 00.0 0.0 00.0 140 01081161 13.2 04.0 12.0 143 0.3 cm 33.4 711 2.1 40.0 45 Slime (untreated) 11.0 64.0 11.9 11.9 6.8

Composite 76.6 70.5 4.9 91.7 18.5 Composite 01.4 00.3 0.2 oaa 42.0 Silica lects n4 21.0 70.5 as 01.5 Bilica Rejects 12.0 7.0 00.0 1.7 00.0

CompositeFeed. 1000 00.0 000 100.0 1000 Composite Feed 100.0 00.4 10.1 1000 100.0

Anionic flotation oi the lime-activated silica flotation reject" which WM rejected 81.5 percent of the silica in the feed with for percent of the night of the feed a loss of only 8.3 percent of the B. P. L. Flotat pgoent of the silica and only tion of the silica from the slime-bearing pulp was con 0 the The untreated and readily achieved. It is therefore apparent that the cleaner phosphate concentrates were our method of flotation is applicable to slimeciently free of 811168 to D considered finished bearing as we" as desnmed pulps' grade. The composited phosphate accounted for a recovery of 98.8 percent or the Example Phosphate in the sample and P Another portion of the Florida phosphate samcent L and Percent ple was ground to pass 65 mesh, deslimed, and s rahtze s ssaz i isu use ea ra e was emp oye 0 Another zso'gmm portion of the activate the silica to anionic flotation. The reo was wet ground in laboratory Mm. agent charge employed in the test was as follows: mill to pass 65 mesh in the presence of hydrated lime equivalent to 12.0 pounds per ton of ore. 1 The ground charge, which had a pH of 11.2 due cmdmme' Rough Bow Clean to presence of hydrated lime, was flocculated er enger and settled readily. The clear, supernatant 1 grind water was carefully decanted from the settled material to avoid loss of solids. The settled material was repulped with 5 liters of fresh tap water and again allowed to stand until the solids had settled. The clear, supernatant water was decanted from the solids and the washing operation was again repeated. The twicewashed pulp had a pH of 9.8 and was substantiall free of hydrated lime. The washed pulp 3.0 minutes- 8 the pulp again briefly conditioned. Air was admitted to the flotation cell and the rouaher froth was removed. Additional tallol and a small quantity of lead nitrate were added to the pulp to The results of the test are as follows:

was then transferred to a laboratory flotation Assay, per cent Dlst., percent cell and enough tap water was added to give a. Product 33 I pulp for flotation containing about 20 percent B. P. L. $10. aP. L. s10. solids. Flotation of the lime-activated silica from the calcium phosphate was effected by the Pho pha c onfollowing rzggents expressed in conventional 00 "gmfig 33 {3,2 :3 pounds per n of Slime (zifit'ritelifl 1010 0412 111s 1110 010 0 its 88.7 05.0 10.4 00.8 41.0 R m Conditioner Rough Scav- Cleaner Silica 11.3 0.0 90.0 1.2 52.4

eage

er enge' N04 55 CompoaiteFeed. 100.0 00.1 10.4 100.0 100.0

g g f g ggg 2 The results of the previously recorded flotation hos ate 1.5 0.04 tests are typical of those we have obtained on 'fiig 8-: samples of deslimed feed from several washers op- Time, min: I 55 2:5 BKY 3. 0 sio ""56 crating in the Florida phosphate district. Flotam6 mo tion of total or deslimed charges of the washer feeds ground in a pebble mill, iron ball-mill, or iron rod-mill to pass 65, 100, or 200 mesh gave results similar to those indicated. A moderate quantity of a metaphoephate or polyphosphate,

such as sodium metaphosphate, sodium hexametaphosphate, or sodium tetraphosphate, in a caustic alkaline pulp having a pH of at least 10, and preferably 11 to 12, adequately retarded the calcium phosphate during flotation of the activated silica. V Hydrated lime and various soluble alkaline-earth and heavy-metal salts, such-as calcium chloride, magnesium sulfate, barium chlorid strontium nitrate, or lead nitrate, were employed and found suitable for activating the quartz and granular silicate minerals to anionic flotation. Tallol, sulfate soap, oleic acid, sodium oleate, flsh oil soap, flsh oil fatty acids, and similar anionic collecting agents were employed in'various tests for flotation of the activated silica and gave good results. The proper quantity of caustic a1- kali, phosphate depressant, activating agent, and collector diflers slightly for different ores and the optimum quantities are best determined by trial for each particular case.

Example IV A synthetic cement rock was prepared by mixing approximately equal quantities of calcite and quartz. The mixture was ground to pass'65 mesh in a laboratory pebble mill and transferred to a laboratory mechanical flotation cell. Tap water was added to the cell to give a pulp containing about 25 percent solids. Flotation of the quartz from the calcite was efl'ected by the following reagents expressed in conventional pounds per ton of flotation teed:

Conditioner Reagent Rougher No. 1 No. 2

Caustic soda Sodium hexametaphospbate Calcium Chloride. Sodium pleate.

Assay percent Dist. percent Weight,

Product per cent CaCOr SiO: C800: SiO:

Calcite concentrate,

rougher 89. 3 l0. 7 Silica rougher froth Composite Feed.

Rougher flotation of the quartz rejected 88.9 percent of the silica with a loss of only 7.0 percent of the calcium carbonate.

Example V Another portion of the synthetic cement rock was ground to pass 65 mesh and floated by the procedure described in Example IV, but in this instance lead nitrate and tallol were employed to activate and float the quartz from the calcite. The silica. rougher froth was cleaned twice by 10 reflecting in the same cell using tap water for dilution. The reagent charge employed in the test was as follows:

Conditioner Cleaner Reagent Rougber N0. 1 No. 2 No. 1 No. 2

Caustic soda. 0.7 Sodium henmetao 4 0 4 The results of the test follow:

Assay, per cent Dist., per cent Weight Product pet C1100: Hi0: 0e00: 8101 Calcite eonoentrate...- 35. 8 09.3 0.7 70. 3 0. 5 Middlings 33.2 39.8 00.2 26.1 40.5 Silica Rejects 31. 0 5. 9 94. 1 3. 6 69. 0

Composite Feed- 100.0 60.6 49.4 100.0 100.0

The calcite concentrate (rougher tailing) and silica rejects (cleaner froth) from the test were of acceptable grade, but the middlings would require retreatment to yield final concentrates and tailings.

Example VI Conditioner Reagent Rougher Scavenger No 1 No.2

Causticsoda-.-.. 1.0 v Sodium hexametaphosphate. 1.0 Sodium oleate 1. 0.4 0.4 2.5 2.5 2.5 11. 2 11. 1 ll. 0

The rougher and scavenger iroths in the tests were sufliciently free of calcite to be rejected without cleaning. Analysis of the calcite concentrate and the combined rougher and scavenger silica froths gave the following results:

W ht Assay, per cent Dist., per cent 61g Product per cent;

CaCO: S10: CaCOa SiOi Calcite Concentrate... 76. 1 90.3. 9. 7 98.1 24. 7 Silica Rejects 23. 9 5. 7 94. 3 1. 9 75. 3

Composite Feed. 100. 0 70. l 29. 9 100. 0 100. 0

centrates.

Example VII In another test on the aforementioned synthetic cement rock wherein lead nitrate equivalent to 1.0 pound per ton of flotation feed was employed to activate the quartz, the calcite concentrates assayed 98.9 percent CaCO: and 1.1 percent 810:, and the silica reiects assayed 21.2 per cent CaCO-a and 78.8 percent 810:.

Example VIII In still another test on the synthetic cement rock,'hydrated lime equivalent to 12 pounds per ton of flotation feed was added to the grinding operation. The ground pulp was washed with fresh tapwater to reject the iiine remaining in 'solution employingthe procedure described. in

Example II. The washed pulp was floated to reject the quartz using 1.0, 0.8, 1.0, and 0.4 pound per ton, respectively, of caustic soda, sodium hexametaphosphate, sodium oleate, and oieate acid. The rougher calcite concentrate assayed 99.0 per cent CaCO: and 1.0 per cent 810:. and accounted for a recovery of 94.1' percent of the calcium carbonate in the feed. The rougher silica froth assayed 13.0 per cent CaCO: and 87.0 percent 810:, and contained 97.6 per cent of the silica in the feed.

Example IX A mixture composed of approximately 8 parts Anionic flotation of the calcium-activated quartz rejected 95.5 percent of the silica in the feed with a loss of 10.8 percent of the barium carbonate (witherite).

In this test. the calcium chloride used to actiate the quartz to anionic flotation was added to the pulp before the alkali and phosphate. While we have found that such practice is permissible on many nonmetallic ores, we generally prefer to add the silica-activating agent to the caustic alkaline and phosphate conditioned pulp. The soluble alkaline-earth or heavy-metal salt to activate the silica may be added before, with, or after of witherit'e and 4 parts of quartz was ground to pass 85 mesh and subjected to flotation in a manner similar to that described in Example IV. Activation and flotation of the quartz from the witherite was efl'ected by the following reagents expressed in pounds per ton of flotation feed:

Conditioner Raget Riggla Scav- No. 1 No. 2 No. 3

Calcium chioride.. l. 0

Caustic soda. l. 0 0. 4 Sodium hexameta- 1 0 o o p flodil oleate. 1. 0 0.10 Oieic mi 0. 4 Time,min 2.6 2.6 2.6 2.6 2.5 2.5 Pulp pH? l1. 2 ll. 2 10. 1 l0. 7 l0. 8

The rougher and scavenger silica i'roths were combined and cleaned once in the same cell using tap water for dilution with caustic soda to maintain alkalinity, sodium hexametaphosphate to retard the witherite, and sodium oleate to insure flotation of the quartz. The results of the test the anionic collecting agent without departing from the spirit of our invention.

Example X Conditioner Reapnt Rougher Cleaner No. 1 No. 2

cm soda. i g g. 4 Calcium chloride I I I 1. o Sodium ole-tn 2. 0 0. l Oleic acid 0. 4 Time, min 2. 6 2. 5 2. ii 2. 5 Pulp pH 11. 2 11. 2 ll. 0 10.9

The results of the test follow:

Assay per cent Dist. cent Weight, Product per cent SICO: 8101 8:001 8102 Btrontianite Concentratee:

Rougher 36. 0 97. 6 2. 4 57. 4 2. l Cleaner 16. 5 88. 8 11. 2 24. 6 4. 5

Composite 61. 5 94. 8 5. 2 82. 0 6. 6 Silica Rejects 48. c 22. l 77. 9 18.0 93. 4

Composite Feed. 1(1). 0 50. 5 40. 5 100. 0 100. 0

Example X! A mixture composed of approximately equal quantities of barite and quartz was ground to pass mesh and subiected to flotation in a manner similar to that described in Example IV. The quantities of reagents, expressed in pounds per ton .of flotation feed, employed for flotation of the quartz from the barite were as follows:

Conditioner Cleaner are as follows: R0

ugh Scav- Reagent er engor A t D t No. 1 No. 2 No. 1 No. 2

ssay per can is rcent Product weight p6 percent Causticsoda 0.7 0.4 0.4

Bacon 8101 BaCO; SiO, Sodium hexametaw L 2.0 0.05 0.10 Witherite Concontrates:

Rougher 45.1 90.0 1.0 70.6 1.1 Cleaner as 840 10.0 12.7 3.4

S' ggmposite 53.9 00.0 3.4 89.2 4.5

m m8 The rougher and scavenger silica froths were CompositeFeed. 100.0 58.4 41.6 100.0 100.0 combined and cleaned twice by refloating in the same cell using tap water for dilution with the reagents as indicated. The results of the test are as follows:

w ht Assay, per cent Dist., per cent erg Product per BaSOl SiOi 3:180; 810,

Barite Concentrates:

ougher 47. 6 93. 9 6. l 94. 2 5. 6 Cleaner 1. 9 65. 4 34. 6 2. 6 l. 2

Composite 49. 92.8 7. 2 96. 8 6. 8 Silica j Rejeets 50. 5 3.0 97. 0 3. 2 93. 2 Composite Feed. 100. 0 47. 4 52. 6 100. 0 100. 0

Example XII A sample of barite table concentrates was obtained from operating plant near Cartersville,

Georgia. The table concentrates containing barite associated with iron oxides and quartz together with minor quantities of feldspar and other silicate gangue minerals were being ground and treated by flotation to reject silica and to recover an enriched barite-iron product. A head analysis of the sample gave 62.6 percent BaSO4, 29.8 percent SiOz, and 5.4 percent FezOs.

A 250-gram portion of the sample was wet ground in a laboratory rod-mill to pass 65 mesh. The ground pulp was transferred to a mechanical flotation cell and diluted with tap water to give a pulp containing about percent solids. Activation and flotation oi the siliceous gangue constituents from the retarded barite and iron oxides was effected by-the following quantities of reagents expressed in conventional pounds per ton of flotation feed:

Conditioner Cleaner Reagent Rougher No.1 No.2 No.1 No.2

Caustic soda Sodium hexameta- The results of the test are as follows:

Assay, per cent Dist per. cent Product gfi ggg B9804 S10: F810: BaS04 SiOa F010:

Barite Concentrstes:

Rougher 62. 3 83. 7 5. 6 7. 9 83. 3 11. 7 91. 9 Cleaner 6.8 56.5 37.3 3.9 6.1 8.5 4.9 Composite... 69. i 81.0 8.7 .7. 5 89. 4 20. 2 96. 8 Silica Relects 30. 9 21. 3 77. 0 0. 6 l0. 6 79. 8 3. 2

Composite Feed 100.0 02.0 29.8 5.4 100 0 100.0 100.0

- ing in solution as calcium carbonate, and therein solution, until said pulp contains not more than 100 parts per million of soluble lime, and then subjecting said pulp to agitation and aeration in the presence of a quantity of caustic alkali to establish a pulp pH at least as alkaline as pH 10, and an alkali-soluble inorganic phosphate selected from the group consistingof metaphosphates and polyphosphates, together with an anion-active collecting agent selected from the class consisting of fatty acids and resin acids and mixtures of fatty and resin acids-and soaps thereof, whereby siliceous gangue is floated and beneflciated nonmetallic mineral is depressed and recovered.

2. A process for beneflciating ores of nonmetallic minerals of the class consisting of calcite, barite, strontianite, witherlte, and tricalcium phosphate containing siliceous gangue materials which comprises blunging an aqueous pulp of the comminuted are in the presence of hydrated lime to establish a pH of at least about 11, then adding thereto soda ash to precipitate the lime remainafter subjecting said pulp to agitation and aeration in the presence of an alkali-soluble inorganic phosphate selected from the group consisting of metphosphates and polyphosphates, together with an anion-active collecting agent selected from the class consisting of fatty acids and resin acids and mixtures of fatty.v and resin acids and soaps thereof, whereby siliceous gangue is floated and beneilciated nonmetallic mineral is depressed and recovered.

employed as the collecting agent.

5 The process of claim 1 wherein oleic acid is employed as the collecting agent.

6. The process of claim 2 wherein sodium hexametaphosphate is employed as the alkali-soluble inorganic phosphate.

7. The process of claim 2 wherin talloi is employed as the collecting agent.

8. The process of claim 2 wherein oleic acid is employed as the collecting agent.

. JULIUS BRUCE CLEMMER.

CARL RAMPACEK.

REFERENCES CITED The following referencesnareeof record in the the of this patent:

UNITED STATES PATENTS Number Name Date 2,363,029 Weinig Nov. 21, 1944 1,780,022 Littleford Oct. 28, 1930 1,914,694 Lange June 20, 1933 1,914,695 Lange June 20, 1933 2,289,741 Tartarton July 14, 1942 2,383,467 Clemmer and Clemmons -L..- Aug. 28, 1945 

